Solar tracking apparatus and solar electric power generation system thereof

ABSTRACT

The present invention provides a solar tracking apparatus for use with a power driving apparatus. The solar tracking apparatus includes: a memory unit for recording a first solar image; an image capturing unit for capturing a second solar image; and an processing unit for obtaining difference between the first solar image and the second solar image; wherein the processing unit activates the power driving apparatus in response to the difference. Furthermore, the present invention also provides a solar power generation system using the solar tracking apparatus. Besides the solar tracking apparatus, the solar power generation system also includes a solar panel; the power driving apparatus for adjusting the position of the solar panel, wherein the processing unit of the solar tracking apparatus activates the power driving apparatus based on the difference so that the solar panel is aligned with the sun to gather the solar energy of the sun.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the right of priority based on Taiwan Patent Application No. 097114033 entitled “solar tracking apparatus and solar power electric generation system thereof”, filed on Apr. 17, 2008, which is incorporated herein by reference and assigned to the assignee herein.

FIELD OF THE INVENTION

This invention relates to a solar tracking apparatus and a solar power generation system thereof, and more particularly to a solar tracking apparatus to track the sun by digital image comparison.

BACKGROUND OF THE INVENTION

A conventional solar tracking apparatus adopts a light sensor to track the sun. The light sensor sends a sensing signal to a power driving apparatus when it senses the “obliquely” incident sun light. In response to the sensing signal, the power driving apparatus adjusts the solar tracking apparatus as well as solar cells aligned with the sun.

Referring to FIGS. 1 and 2, a conventional solar tracking apparatus 1 includes an opaque housing 12, a focusing tube 14, and four light sensors 18. The tube 14 is disposed on the housing 12. The bottom of the housing 12 has a the detection region 16, which could be divided into a region B and a region A enclosing the region B. The four light sensors 18 are disposed at the boundary between the region A and the region B.

While the sun's ray a₁, through the tube 14, illuminates the region B only, the light sensors 18 located around the region B may not be illuminated. Therefore, these four lights will not send any signal to the power driving apparatus (not shown). As time goes by, the sun moves and has the oblique sun ray a₂ illuminate the light sensors 18, and the light sensors 18 sends a sensing signal to activate the power driving apparatus. Accordingly the power driving apparatus adjusts the solar tracking apparatus 1 (as well as the solar cell, not shown) aligned with the sun, and then the sun's ray will illuminate the region B only again and no oblique sun ray is sensed by the light sensors 18. Following this way, the solar tracking apparatus 1 can become aligned towards the sun automatically and achieves the “sun tracking”.

However, the power driving apparatus above is activated only when the light sensors 18 sense the oblique sun ray. Therefore, the solar tracking apparatus 1 may become misaligned before the next time when the light sensors 18 sense the sun again, as shown in FIG. 3.

In a solar power generation system, the power generation capacity depends on the alignment of the solar cell with the sun. FIGS. 3 and 4 show the conventional solar tracking apparatus 1 in the solar power generation. At time t=0, the solar tracking apparatus 1 and the solar cells are best aligned with the sun, and the power generation capacity reaches the maximum (E_(max)). Then at time t=t₁, the alignment is the worst, so the power generation is down to the minimum (E_(min)). At this moment, the light sensors will sense the oblique sun ray, and the power driving apparatus can adjust the solar tracking apparatus 1 and the solar cell towards the sun. As shown in FIG. 4, from time t=0 to t=t₁, the power generation does not have full capacity because of the misalignment more or less.

Furthermore, if the sun's rays illuminate too obliquely the region A without illuminate light sensors 18, the power driving apparatus may not receive any signals to activate the solar tracking apparatus 1. It often happens after the sun is blocked by the cloud for a period time.

Another problem is that the sensitivity of the apparatus 1 is limited. When the region B is large, the alignment of the apparatus 1 to the sun is not very accurate.

Thus, it is desirable to improve the alignment of the solar tracking apparatus to the sun, to track the sun even after the sun is blocked by the cloud for a period of time, and to increase the power generation capacity.

SUMMARY OF THE INVENTION

One aspect of the present invention is to provide an apparatus to track the sun by digital image comparison to achieve accurate alignment to the sun. In another aspect of the invention, the apparatus can predict the sun's position in the sky based on the stored historical data.

In one embodiment, the present invention provides a solar tracking apparatus for use with a power driving apparatus, the solar tracking apparatus includes: a memory unit for recording a first solar image; an image capturing unit for capturing a second solar image; and an processing unit for obtaining difference between the first solar image and the second solar image. The processing unit activates the power driving apparatus in response to the difference.

In another embodiment, the present invention also provides a solar power generation system including: a solar panel; a power driving apparatus for adjusting the solar panel; and a solar tracking apparatus. The solar tracking apparatus further includes: a memory unit for recording a first solar image; an image capturing unit for capturing a second solar image; and an processing unit for obtaining difference between the first solar image and the second solar image. The processing unit activates the power driving apparatus in response to the difference so that the solar panel can be aligned with the sun.

Some advantages may be achieved by using the technical features of the embodiment above, which follows:

-   1. The alignment of the solar tracking apparatus with the sun can be     very accurate, and the power generation has a full capacity. -   2. The solar image can be captured wherever the sun is in the sky,     and the sun can be located even after it is blocked by the cloud for     a period of time. -   3. The solar image comparison can be done by calculating the solar     centers of the solar images. -   4. The solar tracking apparatus can predict the sun's position with     software to quickly follow the sun's move. -   . The solar tracking apparatus can predict the sun's position     according to the historical solar movement data. -   6. The solar tracking apparatus may be calibrated with software.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a conventional solar tracking apparatus.

FIG. 2 is a schematic diagram of the detection region of the conventional solar tracking apparatus.

FIG. 3 illustrates the accuracy of the alignment of the conventional solar tracking apparatus to the sun.

FIG. 4 illustrates the power generation capacity of a solar power generation system having the conventional solar tracking apparatus.

FIG. 5 is a schematic diagram of the solar power generation system in accordance with an embodiment of the present invention.

FIG. 6 is a block diagram of the solar power generation system in accordance with an embodiment of the present invention.

FIG. 7 is a schematic diagram of the processing unit of the solar tracking apparatus in accordance with an embodiment of the present invention.

FIG. 8 illustrates the accuracy of the alignment of the solar panel of the solar power generation system to the sun according an embodiment of the present invention.

FIG. 9 illustrates the power generation capacity of a solar power generation system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The technical features and advantages of the present invention will be illustrated as following, which will be understood and operated by anyone of the ordinary skill in the art. Also the objects and advantages may be best understood by referring to the disclosed context, claims, and drawings. The context of the present invention and the detailed description are described to help clarify the invention, and are not intended to limit the invention from that described in the claims.

Referring to FIG. 5, the solar power generation system 2 includes a supporter 22, a solar panel 24, a solar tracking apparatus 26, and a power driving apparatus 28. The supporter 22 is a pillar to support the whole system 2. The solar panel 24 converts light energy into electrical energy by the photovoltaic effect, and has a light collecting surface 24a, as the conventional solar panel. The solar panel 24 is disposed on the supporter 22 and can be rotated in various directions. In this embodiment, the solar tracking apparatus 26 is disposed on the supporter 22. Meanwhile the solar tracking apparatus 26 and the light collecting surface 24a of the solar panel 24 face the same direction, for example, towards the sun.

As shown in FIG. 6, the solar tracking apparatus 26 includes an optical unit 261, an image capturing unit 262, an processing unit 263, and a memory unit 264. The optical unit 261 is a convex lens to focus the sun light onto the image capturing unit 262. Note that the optical unit 261 is optional. It could be embodied as a common convex lens and/or a wide-angle lens. If the optical unit 261 is embodied as a common convex lens, it may focus the sun light onto the image capturing unit 262 only when the sun is in a small particular range of position in the sky. If the optical unit 261 is embodied as a wide-angle lens, the sun's position can be in a wide range. These will be illustrated more detail below.

The image capturing unit 262 can capture an object's digital image. It includes a sensing element (not shown) to sense the light and then transform light energy into electrical signal. The image capturing unit 262 can be embodied as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS). In the first embodiment of the present invention, it is embodied as a CCD to capture the solar images.

The processing unit 263 is disposed at the output of the image capturing unit 262, and it can configure the electrical signals from the image capturing unit 262 to form a complete digital image. The digital image can be further processed via a software program. In addition, the processing unit 263 can compare two or more digital images and obtain the difference therebetween. Details of this part will be described later.

The memory unit 264 records all kinds of data and particularly, provides the recorded data to processing unit 263 for the image comparison. In an embodiment, the memory unit 264 records the solar images generated by the processing unit 263, the image difference concluded by the processing unit 263, and the historical solar movement data.

The power driving apparatus 28 such as a motor is disposed on the supporter 22. It rotates the solar tracking apparatus 26 and the solar panel 24 on the supporter 22, so that the solar tracking apparatus 26 and the solar panel 24 can be aligned with the sun. The power driving apparatus 28 could be referred to a power driving apparatus adopted in the conventional solar power generation system.

The following is to explain how to align the solar tracking apparatus 26 and the solar panel 24 with the sun by digital image comparison. First, the sun light is focused on the image capturing unit 262 by optical unit 261. Next, the image capturing unit 262 captures a solar image, or several solar images each after a predetermined time interval. The predetermined time interval, for example, can be one or two seconds, so that the image capturing unit 262 can capture many solar images within a period of time. For example, if the predetermined time interval is set as 1 second, the image capturing unit 262 will capture 60 solar images in 1 minute.

FIG. 7 illustrates the image comparison conducted by the processing unit 263. A reference solar image 2642 may be recorded in the memory unit 264 in advance. The reference solar image 2642 could be a captured solar image taken in advance or generated purely by a computer. A captured image 2622 to be compared is captured by the image capturing unit 262 on the spot and generated by the processing unit 263. As shown in FIG. 7, the reference solar image 2642 includes a first calculated solar center 2644, and the captured solar image 2622 includes a second calculated solar center 2624. The processing unit 263 compares the first solar center 2644 with the second solar center 2624 and obtains a displacement in x direction (Δ_(χ)) and in y direction (Δy) between the first solar center 2644 and the second solar center 2624. The displacement corresponds to the angle to be adjusted of the solar panel 24 and the apparatus 26.

In addition, the displacement can be stored in the memory unit 264 to activate the power driving apparatus 28 in the future. Also, the power driving apparatus 28 can adjust the solar panel 24 immediately based on the displacement so that the second solar center 2624 of next captured image and the first solar center 2644 of the reference solar image will be more similar, and the solar panel 24 is aligned better with the sun.

Note that the solar centers described above can be calculated by the software, even when part of the sun is blocked by a cloud. Also note that in addition to the displacement of the solar center, other kinds of difference between the reference image and the captured image could be adopted, as long as the difference can characterize the position of the sun.

Referring to FIGS. 8 and 9, by comparing the reference image and the captured image, the misalignment of the solar panel 24 to the sun could be suppressed to a degree, particularly if the predetermined time interval is short (such as one second). Therefore, the power generation capacity of the solar power generation system 2 could be increased.

In addition, after the sun's movement is detected by the image comparison, the sun's movement data can be further recorded in the memory unit 264. The data may include historical movement data obtained yesterday, one year ago, four years ago, etc. The memory unit 264 can further provide these data for the processing unit 263 to activate the power driving apparatus 28 without performing image comparison on the spot. Then the power driving apparatus 28 can align the solar panel 24 with the sun based on these data. Also, while the sun is blocked by the cloud for a period of time, the power driving apparatus 28 could adjust the solar panel 24 based on these data. Therefore, while the cloud goes away and the sun appears next time, the sun can be tracked by the image comparison again and the solar panel 24 can be aligned with the sun accurately.

Another embodiment of the optical unit 261, it can be embodied as a wide-angle lens to focus the sun light onto the image capturing apparatus 262 wherever the sun is in a wide rage of positions in the sky. Therefore, the image capturing unit 262 could capture the solar image easily.

In addition, a common convex lens and a wild-angle lens can be used together in the solar power generation system 2. First, the wild-angle lens is adopted to focus the sun light wherever the sun is in the sky and a first captured solar image is generated by the image capturing unit 262. By comparing the first captured solar image with the reference solar image, the solar panel 24 can be roughly aligned in preliminary. Next, the common convex lens is adopted and a second captured solar image is generated. By comparing the second captured solar image with the reference solar image, the solar panel 24 can be further aligned exactly.

Although the invention illustrated herein is embodied in above examples, it is not intended to limit the invention. The structural changes and modifications belong to the protective scope without departing from the aim and the scope of the invention. The scope of claims as defined in the present invention can refer to the following claims. 

1. A solar tracking apparatus for use with a power driving apparatus, the solar tracking apparatus comprises: a memory unit for recording a first solar image; an image capturing unit for capturing a second solar image; and an processing unit for obtaining a difference between the first solar image and the second solar image; wherein the processing unit activates the power driving apparatus in response to the difference.
 2. The solar tracking apparatus of claim 1, wherein the first solar image is a default reference solar image, and the second solar image is a solar image taken on the spot.
 3. The solar tracking apparatus of claim 1, wherein the processing unit further calculates a first solar center from the first solar image and a second solar center from the second solar image, and the difference is obtained by comparing the first solar center with the second solar center.
 4. The solar tracking apparatus of claim 1, wherein the difference is recorded in the memory unit to provide the processing unit to activate the power driving apparatus in advance.
 5. The solar tracking apparatus of claim 1, further comprising an optical unit for focusing the sun light onto the image capturing unit to form the second solar image.
 6. The solar tracking apparatus of claim 5, wherein the optical unit is a lens.
 7. The solar tracking apparatus of claim 5, wherein the optical unit is a wide-angle lens.
 8. The solar tracking apparatus of claim 1, wherein the image capturing unit is a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS).
 9. The solar tracking apparatus of claim 1, wherein the image capturing unit further captures a plurality of second solar images, and each second solar image is taken after a predetermined time interval.
 10. A solar power generation system includes: a solar panel; a power driving apparatus for adjusting the solar panel; and a solar tracking apparatus including: a memory unit for recording a first solar image; an image capturing unit for capturing a second solar image; and an processing unit for obtaining difference between the first solar image and the second solar image; wherein the processing unit activates the power driving apparatus in response to the difference so that the solar panel can be aligned towards the sun to gather sun light.
 11. The system of claim 10, wherein the first solar image is a default reference solar image, and the second solar image is a solar image taken on the spot.
 12. The system of claim 10, wherein the processing unit further calculates a first solar center from the first solar image and a second solar center from the second solar image, and the difference is obtained by comparing the first solar center with the second solar center.
 13. The system of claim 10, wherein the difference is recorded in the memory unit to provide the processing unit to activate the power driving apparatus in advance.
 14. The system of claim 10, further comprising an optical unit for focusing the sun light onto the image capturing unit to form the second solar image.
 15. The system of claim 14, wherein the optical unit is a lens.
 16. The system of claim 14, wherein the optical unit is a wide-angle lens.
 17. The system of claim 10, wherein the image capturing unit is a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS).
 18. The system of claim 10, wherein the image capturing unit further captures a plurality of second solar images, and each second solar image is taken after a predetermined time interval. 